Yale Scientists Unveil ‘Anti-Laser’ Technology

A new antilaser device absorbs laser beams so well that barely a scrap of energy escapes. But if its whimsical name conjures up Star Wars–style visions of laser armor, curb your enthusiasm.

Photo: Yidong Chong/Yale University

“This is the worst laser shield you could ever invent,” says Douglas Stone, a physicist and member of the Yale team that describes the device in the Feb. 18 Science. Because the antilaser soaks up energy, “R2-D2 would melt into a puddle if protected by our device.”

Instead, the prototype antilaser — which absorbs only a narrow range of infrared wavelengths — may be useful for designing light-based devices integrated into electronic computer chips.

Other researchers have created similar devices, called coherent perfect absorbers, by repeatedly bouncing light between a mirror and a piece of absorbing material. What’s new, Stone says, is the discovery of the fundamental principle that makes these devices work: time reversal.

In the context of lasers, time reversal isn’t a way for scientists to travel back to childhood and fix their embarrassing mistakes. It’s a technique for rewinding and undoing a process by reversing the mathematics underlying it — in this case, by changing a plus sign to a minus sign to make the energy absorbed by the antilaser equal to the energy produced by a laser…